The Nucleus. Robin Bauman Advanced Bio Mr. Daly. The Nucleus. Highly specialized organelle that serves as the information processing and administrative center of the cell. Two major functions Stores the cell’s hereditary material (DNA) Coordinates cell’s activities
nucleus and the
Ribosome is a particle composed of protein and RNA that serves as the site of protein synthesis
Found in cytoplasm of prokaryotic and eukaryotic cells
Has a large and small subunit that act as one to read the genetic sequence from the mRNA to make proteins
“Using the mRNA as a template, the ribosome traverses each codon, pairing it with the appropriate amino acid. This is done through interacting with transfer RNA (tRNA) containing a complementary anticodon on one end and the appropriate amino acid on the other.”
Large Subunit- mostly RNA, “Proteins are distributed mainly on the surface. Some proteins have long tails that extend into the interior of the complex. These tails, which are highly basic, interact with the negatively charged RNA.
The active site domain for peptide bond formation is essentially devoid of protein. The peptidyl transferase function is attributed to the 23S rRNA, making this RNA a ‘ribozyme’.“
Small Subunit- a cleft in the small subunit is the binding site for tRNA. Small subunit is also really flexible and can assume different conformations.
In eukaryotes, ribosomes are made up of 4 strands of RNA & are often attached to the membranes of endoplasmic reticulum to form Rough ER
In prokaryotes, ribosomes are made of 3 strands of RNA & occur free in cytoplasm
Ribosomes in translation 40% protein and 60% ribosomal RNA (rRNA)
- Free: are found in cytosol
- Bound: are bound to rough ER or in the nuclear envelope.
First observed in mid-1950’s by Romanian cell biologist George Palade using an electron microscope.
George Palade won the Nobel Prize for his discovery.
Scientist Richard B. Roberts in 1958 proposed the name “ribosome”.
Made up of two subunits, called large and small subunits.
These subunits consist of proteins and RNA molecules named ribosomal RNA’s (rRNA’s).
About two-thirds of the mass of a ribosome consist of rRNA, either three molecules in prokaryotes or four in eukaryote.
These subunits are made in the nucleolus
The main difference between these two ribosomes is that Eukaryote ribosomes are slightly bigger and slightly differ in their molecular structure.
Ribosomes found in chloroplasts and mitochondria of eukaryotes also consist of large and small subunits bound together with proteins.
Descendents of bacteria and this is why their ribosomes are similar to bacteria.
They are the “workhorses” of protein biosynthesis which is the process of translating mRNA into proteins.
Build proteins from the genetic instructions held with the messenger RNA.
Translate messenger RNA to build polypeptide chains using amino acids delivered by transfer RNA.
1. P-site (peptidyl-tRNA): hold the tRNA carring the growing polypeptide chain
2. A-site (aminoacyl-tRNA): holds the tRNA carrying the next amino acid to be added to the chain.
3. E-site: the exit site where the tRNA leaves the ribosome.
By: Aaron Gjullin
September 24, 2009
The SER has functions in several metabolic processeshttp://liquidbio.pbworks.com/f/1194817600/endoplasmic%20reticulum.jpg
Synthesizes lipids and steroids
Synthesizes the metabolism of carbohydrates
Regulates calcium concentrationFunctions of the Smooth ER
By: Nikki Chase
By: Nikki Chase
Transport Vesicles are tiny membranous sac in a cell, that are involved in shuttling cargo from the interior of the cell, to the cell surface, and from the surface of the cell to the interior the cell. They also provide movement of materials in and around the cell.
Most common example of a Transport vesicle movement, is the transfer of proteins from the rough (ER) to the Golgi Apparatus.
Transport Vesicles are protected from the cytosol by a least one phospholipid bilayer.
Transport vesicles can fuse their phospholipid bilayer with the cell membrane to release waste or other materials outside of the cell. Or can also fuse with other organelles within the cell.
Transport Vesicles are from through the Endomembrane Hypothesis. The vesicles are made though the folding of membranes.
Vesicle trafficking- vesicles that travel over a large distance to get to their target.
Vesicle tethering- is the liking of a vesicle to its target form a further distance. Vesicle fusion may not always occur.
Vesicle docking- docking refers to the holding of two membranes together, and needs to occur for bilayer fusion.
Vesicle fusion- the transportation vesicle phospholipidbilayer, attaches to cell membrane or surface of other organelles. The substance inside the vesicles is then released out of the cell or into other organelles of the cell. This fusion process also adds phospholipids to the cell membrane due to the fact that vesicle is completely absorbed to the entire cell membrane.
The Mechanism of Vesicular Transport,
The Mechanism of Vesicular Transport,
Endomembrane System, http://academic.brooklyn.cuny.edu/biology/bio4fv/page/endomem.htm
← http://liquidbio.pbworks.com/f/1194817600/endoplasmic%20reticulum.jpgAn electron micrograph of a Lysosome
Diagram of a Lysosome→
By Isaac Rubin
The Power Center of the Cell
Mitochondria can have different shapes, but all serve the same function.
Dual Membrane structure
Inner membrane and Outer membrane
The Space in between the membranes is the intermembrane space.
Inner membrane is folded (SA/V ratio), and the folds are called CRISTAE.
The Cristae are where oxygen and sugar are combined to create ATP-the main source of energy for the cell.
The Area inside the folded inner membrane is called the matrix.
Mitochondria have their own DNA
DNA similar to that of bacteria
Endosymbiosis- small species of bacteria survived ingestion by a Prokaryote and was incorporated into the cytoplasm- where it then evolved into the organelle it is today.
Evolution- cells capable of the creation of energy would have a serious advantage over other cells- natural selection
By Emily Schwab
Structural role is to bear tension from forces pulling in different directions
Makes a three-dimensional support system just inside the plasma membrane to support the cell’s shape
Bunches of microfilaments also make up the core of microvilli, which increase a cell’s surface area
Electron Micrograph Imageshttp://www.dwm.ks.edu.tw/bio/activelearner/04/images/ch04c5.gif
Form Cilia and Flagella.
Replicate in interphase stage of mitosis.Evolution Function
Flexible extensions of cell. division.”
Cilia are the many short extensions of the cell, and flagella are the one or two long extensions.
The evolution of cilia and flagella have not yet been determined.Cilia and Flagella
Flagella cross section division.”
Their function is to create the main source of movement for the cell and bring food particles into the cell.
They not only allow the cell itself to move, but they also allow liquids and particles to move across their surface.
Ex) moving the egg from the ovary through the fallopian tube
They have 9 sets of 2 microtubules inside. Collected, they are called “axoneme”.Cilia and Flagella
Movement is caused when ATP is present, causing a bending motion of the microtubules inside the cilia and flagella.
The bending motion of the microtubules is caused by a protein called “dynein”. Dynein is located in between the sets of microtubules. It pulls one set down and then releases it, causing the other to bend and then bounce back up.Cilia and Flagella
By: Nikki Vinyard